1. Field of the Invention
The present invention relates to channel capacity estimation and prediction for rate adaptive wireless video; and, more particularly, to channel capacity estimation and coding rate adjustment method for adaptive video transmission, and video transmission/reception apparatus using the same, which can increase coding rate adaptation by precise channel capacity prediction to improve the quality of wireless video, by optimally adjusting, at a video transmission apparatus (server), video/channel coding rates based on a channel capacity estimate, which is estimated by using Bit Error Rate (BER) of a received packet and then feedbacked by a video reception apparatus (client).
This work was supported by the IT R&D program of MIC/IITA [2006-S-103-02, “Development of Ubiquitous Content Access Technology for Convergence of Broadcasting and Communications”].
2. Description of Related Art
In radio environments, lots of bit errors may occur due to weak signal strength, which result in loss of packets. Therefore, in order to decrease this packet loss in a radio terminal, it is required to estimate link quality or channel status. In particular, for real-time video adaptation, it is necessary to precisely estimate radio channel capacity in real time. This is because link quality is seriously affected by interference, fading, multi-path effects, mobility, and so on, which causes a severe change in channel capacity.
One of prior arts for estimating link quality or channel status is a radio LAN protocol (Conventional protocol: “CON protocol”) which discards packets having one or more residual error (MAC layer error). This protocol estimates link quality (channel capacity) by using Packet Error Rate (PER), as in the following equation:
                                          C            ~                    n          CON                =                              1            -                                          1                m                            ⁢                                                ∑                                      i                    =                    1                                    m                                ⁢                                                                  ⁢                                  Z                  i                                                              =                      1            -            PER                                              Eq        .                                  ⁢                  (          1          )                    
wherein Zi denotes a checksum (Zi=1 if checksum fails) and PER represents a packet error rate.
However, since this prior art method predicts link quality or channel capacity by using PER, not BER, the accuracy of such prediction is lowed to decrease channel adaption, thereby making it impossible to guarantee the desired quality of wireless video.
Meanwhile, as attempts to reduce packet loss in a radio terminal, lots of studies on Cross-Layer Design (CLD) protocol have actively been made in recent years. As well-known in the art, the CLD protocol refers to a technology that transfers packets with bit errors to an upper layer for utilizing them therein.
The fact that many studies to date can increase video throughput through the use of CLD was verified. Moreover, it was also verified that the existing radio LAN can utilize side information, which is important information capable of estimating channel status. Here, the side information contains Signal to Silence Ratio (SSR) (where SSR corresponds to SNR parameter) and checksum.
In addition to the perception about the importance of such side information, the CLD protocol utilizing side information, that is, Cross-Layer Design with Side Information (CLDS) protocol has appeared. This CLDS protocol can be applied very usefully to real-time video rate-adaptation. Especially, it is expected that the link quality based on CLDS will be estimated more precisely by using the entropy of residual error process.